Last week, SpaceX made history with the successful launch of its Falcon Heavy rocket — the most powerful launch vehicle since the Saturn V that sent men to orbit the Moon. Carrying a Tesla Roadster as part of its historic payload, the Falcon Heavy’s success has ushered in a new era of human spaceflight, even as the Roadster and its spacesuit “passenger” embark on an elliptical orbit around the Sun, passing Mars and flying through the main asteroid belt on its journey. Moments later, the rocket’s two boosters successfully landed back on Earth; even a missed landing by the central portion of the vehicle couldn’t mar the company’s major success.

But success was not assured — nor was it cause for anything but awe, wonder, and excitement, even from SpaceX CEO Elon Musk. During this historic event, a camera crew from National Geographic captured the anticipation and elation from Musk and his team in preparation for the upcoming new season of the series MARS, returning in fall 2018. MARS blends science fact with science fiction to offer the closest look you’ll get at what it will be like to land and live on the Red Planet until we actually achieve it.

In preparation for the second season of MARS, which is returning to Nat Geo this fall, a camera crew followed Musk and his team on the day of the launch, capturing their reactions as the rocket rumbled to life.

“Holy flying f--k, that thing took off,” Musk exclaimed. Moments later, he and SpaceX staffers ran out the door of the launch control center and turned their gazes upward. “Look at that! That's unreal!” Musk cried out.

But as Musk emphasized before and after the launch, success was hardly a given.

SpaceX announced its intention to build the Falcon Heavy in 2011, crafting it as a vehicle essentially made out of three combined Falcon 9s, the company's currently most-used rocket. At the time, Musk thought that the Falcon Heavy would launch in 2013, but the project promptly entered years of development hell. To make the Falcon Heavy work, SpaceX had to redesign the center booster completely, rework the control systems, and upgrade the fins that the reusable first stages use to steer so they can land back on Earth.

“We tried to cancel the Falcon Heavy program three times at SpaceX, because it [was] way harder than we thought," said Musk in a press briefing after the launch.

Now that the Falcon Heavy has flown, more work remains to refine the rocket and develop its successor, the so-called BFR booster and spaceship that he hopes will one day be bound for Mars. But above all, Musk's takeaway from the test flight was that he and his roughly 7,000 employees had pulled off something extraordinary.

“Crazy things can come true,” he said. “When I see a rocket lift off, I see a thousand things that could not work, and it's amazing when they do.”